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SubjectRe: BUG: ib_mad ftrace event unsupported migration
On Wed, Nov 02, 2022 at 07:44:57AM -0400, Steven Rostedt wrote:
> > before starting throwing some patch into the the air I would like to align with you the approach we should take here.
> >
> > my suggestion here :
> > - ftrace infra should verify no migration happen (end and start happens on same CPU) in case not we will throw warning for the issue .
>
> The scheduler should have. On entering the ring buffer code
> ring_buffer_lock_reserver() it disables preemption and does not
> re-enable it until ring_buffer_unlock_commit().
>
> The only way to migrate is if you re-enable preemption. WHICH IS A
> BUG!

So what on earth did that?

I'm guessing some driver's query_pkey op, but AFAIK we don't have any
explicit pre-emption reenablements in the code - unless it is sneaky..

Leonid what driver are you testing?

Jason

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